4,681 research outputs found
Synthesis of Biodiesel from a Crude Blend of Palm Oil and Rubber Seed Oil
Biodiesel industry is expanding as new challenges arise from environmental impacts
caused by hydrocarbon based fuels. However, the industry has shown some downfall
recently due to the increasing demand of vegetable oils for human nutrition's need.
Crude rubber seed and palm oils were used in this study to synthesize biodiesel since
both can be extracted and produced here in Malaysia from their abundant plantations.
The respective oils and the blends were characterized. An equi-volume blend of crude
palm oil and rubber seed oil was chosen for biodiesel synthesis and exhibited the
following properties: density of0.91754 g/cm3, viscosity of39.35cP, heating value of
38.1 MJ/Kg, acid value 31.4, FFA 11.9%, refractive index of 1.465, mono-,di- and
triglycerides were 2.5, 7.3 and 70 wt%. Sulfur content was acceptable at 0.03 lwt%.
Fstty acid composition for the oil blend was established and the calculated iodine
value was 106.3. Two stage transesterification is performed in this study to remedy
the high acid value of the oil blend. Design of experiments using taguchi technique
was used to study the interaction of parameters involved in the production.
Temperature, alcohol and catalyst amount were studied independently for both acid
and base reactions to find their relevant effects. The optimum operating conditions for
acid esterification which could reduce the FFA% to lower than 0.6% were 65°C, 15/1
methanol to oil ratio and 0.5wt% catalyst. The optimum operating conditions for base
transesterification were 55°C, 8/1 methanol to oil ratio and 2wt% potassium
hydroxide which could achieve the highest possible conversion to methyl esters
exceeding 98 %. The quality of biodiesel produced matched that of international
standards. The kinetics of free fatty acids alcoholysis in acid esterification was
investigated and the rate equation had a reaction order of (2.24). Rate constant was
(6.769xl03 lit/gmol.min) while the activation energy and Arrhenius constant were
60.289 and 14.06 x 109 KJ/g respectively. A nonlinear model was developed and
with experimental data to predict FFA concentration change throughout the reaction.
Kinetics of methyl ester formation in base transesterification was studied using
differential method. Three techniques were applied, namely, graphical method, finite
difference and linear regression. None of which could predict a rate law to represent
the reaction. Consequently, a model was developed to represent the rate of reaction
and the system using nonlinear regression of the experimental data
GSU Event Portal
This sophisticated web application, GSU Event Portal, would allow visitors to search for events happening around the city with the ability of paying for interested up-coming event using a debit/credit card. As the name implies, this web application would display tangible information of such event to event goers. The technology behind this application is to make visitors more informative and feature in dynamic events which might be live music, live festivals and many more. On the user interface, visitors should be able to search for up-coming events by city, time and event type. The result of the search would provide all events that will be happening at the specified time based on a visitor’s search criteria. Event organizers would as well be able to advertise their events ahead of time. The web application will be available on any device that could browse with internet connected and will be designed in three consoles: The Organizer console, Admin console and user interface. Organizer console will be able to create and edit events, view registration for an event and verify payments. The Admin console will be able to give permissions to Organizers and visitors, edit user’s profile and delete user account. The User interface console will be available to visitors and users who would like to register for an up-coming event. In addition to that, it will include map functionality that will show the event location on map. Visitors can only view event listings but to participate in an event, registration would be required for allocation of space
Multilayer nanoparticle arrays for broad spectrum absorption enhancement in thin film solar cells
In this paper, we present a theoretical study on the absorption efficiency
enhancement of a thin film amorphous Silicon (a-Si) photovoltaic cell over a
broad spectrum of wavelengths using multiple nanoparticle arrays. The light
absorption efficiency is enhanced in the lower wavelengths by a nanoparticle
array on the surface and in the higher wavelengths by another nanoparticle
array embedded in the active region. The efficiency at intermediate wavelengths
is enhanced by the simultaneous resonance from both nanoparticle layers. We
optimize this design by tuning the radius of particles in both arrays, the
period of the array and the distance between the two arrays. The optimization
results in a total quantum efficiency of 62.35% for a 300nm thick a-Si
substrate.Comment: - Article Published in Optics Express on 7 Apr 2014. Link:
http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-22-103-A80
Reduced Complexity Optimal Hard Decision Fusion under Neyman-Pearson Criterion
Distributed detection is an important part of many of the applications like wireless sensor networks,
cooperative spectrum sensing in the cognitive radio network. Traditionally optimal non-randomized
hard decision fusion rule under Neyman Pearson(NP) criterion is exponential in complexity. But
recently [4] this was solved using dynamic programming. As mentioned in [4] that decision fusion
problem exhibits semi-monotonic property in a special case. We use this property in our simulations
and eventually apply dynamic programming to solve the problem with further reduced complexity.
Further, we study the e�ect of using multiple antennas at FC with reduced complexity rule
Development of Powder Metallurgy (PM) compacted Cu-TaC electrodes for EDM
The main aim of this paper is to investigate the properties of Cu-TaC electrodes produced by Powder Metallurgy (PM)
method. The design of Experiment (DOE) method was used to plan the investigation. Two different compositions of the powders (Cu-TaC with 30 and 55 % wt TaC) were used. The major properties which determine suitability of electrodes for Electro Discharge Machining (EDM) are electrical conductivity, thermal conductivity and to some extent density. These properties were measured for the green compacted electrodes, analyzed and compared with their sintered counterparts. This is the initial stage to determine the suitability or otherwise of the compacted electrodes. The results showed that the compacted electrodes in green form can be suitable for EDM, since the electrical conductivities are very high (94.96-189.92�-1m-1). The thermal conductivity is good (29.70-33.20W/ m K). The density ranges between 6.13 and 9.80 g/cm3. The sintered electrodes were found to be unsuitable at the specified conditions, because they became non-conductive electrically after sintering. Current efforts are geared towards improving these properties for the sintered ones and also determining their optimum levels
A Hierarchical Approach for Investigating Social Features of a City from Mobile Phone Call Detail Records
Cellphone service-providers continuously collect Call Detail Records (CDR) as
a usage log containing spatio-temporal traces of phone users. We proposed a
multi-layered hierarchical analytical model for large spatio-temporal datasets
and applied that for the progressive exploration of social features of a city,
e.g., social activities, relationships, and groups, from CDR. This approach
utilizes CDR as the preliminary input for the initial layer, and analytical
results from consecutive layers are added to the knowledge-base to be used in
the subsequent layers to explore more detailed social features. Each subsequent
layer uses the results from previous layers, facilitating the discovery of more
in-depth social features not predictable in a single-layered approach using
only raw CDR. This model starts with exploring aggregated overviews of the
social features and gradually focuses on comprehensive details of social
relationships and groups, which facilitates a novel approach for investigating
CDR datasets for the progressive exploration of social features in a
densely-populated city
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